January 14th 2022

Case Study: Thermal & Airflow Modelling in IESVE

Case Study: Thermal & Airflow Modelling in IESVE

ASHRAE BEAP certified freelance consultant, Rade Djukanovic, has used IESVE extensively on a range of public and private sector buildings in Serbia, primarily focusing on thermal and airflow modelling to improve energy efficiency for reconstruction projects. 

For several of these projects, which span kindergartens, schools, hospitals and offices, a detailed energy audit was carried out and thermal modelling in IESVE was used to analyse, evaluate and propose which energy saving and indoor comfort improvement measures would produce the best outcomes.

In these projects, the energy consumption results from the thermal modelling performed in IESVE were compared with actual energy use from the building energy bills. Thermal and air quality comfort measurements collected via data loggers were used to determine actual indoor air temperatures, humidity and CO2 concentration within the buildings. This data was then used to calibrate the IESVE simulation model to closely replicate actual energy consumption and the operational conditions within each building, providing an accurate baseline for further analyses.

Using the MacroFlo application within the software, zone airflow modelling of natural ventilation, combined wind pressure and buoyancy effect was modelled together with hourly thermal simulations in ApacheSim to determine the effectiveness of natural ventilation strategies within the kindergartens and schools. As the measurement campaign only took place over a limited period, simulations were run to determine the CO2 concentration in rooms with various occupancy profiles, thermal and airflow conditions.

Different control strategies were then analysed to evaluate the combined use of natural ventilation with window openings as well as mechanical ventilation, to achieve the maximum energy savings potential of each project. 

Control strategies were investigated in the context of different building load conditions and outside weather conditions, including the implementation of a mechanical ventilation system which would provide cooling with 100% fresh air and without recirculation systems. This control strategy was proposed for the prevention of COVID and other viral infections with the use of low filtration efficiency recirculation systems.

IES thermal modelling was also used to evaluate the operation of air source heat pump systems. ApacheLoads was used to determine the building thermal load for different envelope insulation measures and thermal modelling in ApacheSim was used to evaluate heat pump efficiency for different outside air conditions.

The Suncast application was also used to evaluate the impact of shading on thermal loads and indoor comfort, including dynamic analysis of shadows from adjacent buildings and trees, providing a comprehensive insight of building performance across each project.

“IESVE is a great tool, not only for energy calculations, but also for the simulation of thermal and indoor air comfort. The combined use of MacroFlo zone air flow modelling and ApacheSim for detailed thermal analysis made it possible to simulate different weather and climate conditions, that could not be captured within the limited time for data logging, to evaluate control strategies for combined natural and mechanical ventilation, based on measured results.”

Rade Djukanovic, ASHRAE BEAP Certified Building Energy Assessment Professional